After 4 months of constant company, even being by myself for one night felt foreign again.
I think we can get used to anything with sufficient time. At least one psychological study seems to agree, in which people's relative mood returned to normal within a year of either winning the lottery or losing their legs. 
The weirdness of 2020 had me living with other people again — my girlfriend and then my parents — these last 4 months. By my estimate, during that span I hadn't been alone for more than 4 hours at a time.
Walking into my own apartment yesterday afternoon felt unexpectedly weird.
- My 65" TV struck me as being huge again after only using <=47" screens for so long.
- All the water had evaporated from the bottom part of my toilet.
- My mailbox slot was at capacity — though that's on me for spending airline miles on Time magazine, which I soon discovered is a crappy (subjective) read and now it just gets recycled.
Being on my own for just one night again was tough. Admittedly I wasted time, ordered food and watched a bunch of HBO Max. Those were my go-to coping mechanisms.
Yet, waking up this morning, I started to feel like "my old self" — me from June 2019 onward who's accustomed in this apartment.
- Woke up a couple hours earlier than my traditional time at my parents'.
- Cleaned the whole apartment.
- Knocked out a bunch of "side project" programming and research.
- Planned a snowmobiling trip to at least get some travel in this winter, should international travel continue being restricted.
- Wrote this blog post. 😮
Presumably 100% comfort will arrive within a couple days now.
Before I have written about how my first time ever living alone messed me up big time. Until it became clear that productively using what felt like an eternity was the best thing for me.
How do you learn to be alone? The advice I can offer is to just wait it out. We can seemingly get used to anything with enough time.
Don't wallow around in unhealthy behaviors, though. Maybe my quarantine survival guide can help there.
Good luck. 🎰
 Brickman P, Coates D, Janoff-Bulman R. Lottery winners and accident victims: is happiness relative?. J Pers Soc Psychol. 1978;36(8):917-927. doi:10.1037//0022-35126.96.36.1997